MOTOGP » Stoner keeps 'new set-up' on top

actually the front of the female anatomy yes?

I guess the crack by Telefonary is a joke otherwise he/she is interested in Jack.

Jack,
"more weight on them means more ground pressure and less grip"
Cobbl..s! More ground pressure means less mu but as mu drops off much more slowly than the load increases, the net result is more grip. Mech Eng BSc 1 Physics BSc 0

Thanks Eadgbe I thought I was going mad, I'm neither a scientist nor a bachelor but I always thought that you needed load otherwise how would the tyres grip and collapse to give a bigger grip surface, with no load the bike would slide away, certainly in cars the whole idea is to increase load through corners to improve grip....

Telefonary- thanks for proving me right.

eadgbe- If you want a conversation please don't turn it into a match. We are having enough of this bull**** here already. You are wrong because you forget that vertical load becomes also sideways load (in a linear way) when you are trying to turn. If you get down with the equations you'll see that if you create a function that combines friction coefficient with velocity and turn radius the weight is irrelevant. Of course the friction coefficient isn't a given number but changes with ground pressure and so weight in the end DOES become relevant but not in the way our intuition tells us.

For the doubters, read "Motorcycle handling and chassis design" by Tony Foale, a very interesting read (more than 600 pages!). Foale says that you have a 10% reduction in grip each time you double the weight.

In English please Jack, do you mean that the lighter the bike the better the grip??(providing the tyres work)and is there a stage when the bike becomes too light??

Well, there seems to be some misunderstanding here, I suspect me and eadgbe are saying the same thing. With "grip" I mean the sideways acceleration the bike can create, which means how hard (or fast in other words) the bike can turn. I think eadgbe means the centripetal force alone. If this is the case we are both right.

In english: the bike turns faster when it becomes lighter. There is a limit to that because of necessities in chassis rigidity and also because of implication created by a large unsprung-to-sprung ratio (if the wheels are heavy compared to the rest of the vehicle you have a reduction of grip). You can also have an increase of grip if you make the tyres wider.

In very simple words:

a bike can turn as fast as: (How good your rubber is)*(how wide your tyres are)*(how light your vehicle is). This doesn't count for the wet and how fast the bike can flick from side to side (for this you want narrow tyres) so overall you end up making compromises.

Try playing with a used tyre and throw it rolling sideways on the road, you'll see it can achieve insane lean angles!

Bet Peter Williams would understand!